The present invention is directed to a method for making certain hydroxy-terminated arylene ethers, such as 4,4'[arylbis(oxy)]bisphenols included within the formula, EQU HO--R.sup.1 --O--R--O--R.sup.1 --OH, (1)
where R is a member selected from the class consisting of C.sub.(6-36) arylene groups and C.sub.(6-36) arylene groups substituted with monovalent radicals inert during hydroxy-terminated arylene-forming reactions, R.sup.1 is a member selected from the class consisting of C.sub.(6-20) divalent arylene radicals and C.sub.(6-20) divalent arylene radicals substituted with monovalent radicals inert during hydroxy-terminated arylene ether-forming reactions. The hydroxy-terminated arylene ethers of formula (1) are made from certain dihydroxyaromatic compounds defined below. The hydroxy-terminated arylene ethers of formula (1) are useful as flexible spacers in liquid crystalline aromatic polyesters.
Prior to the present invention, certain 4,4'[arylbis(oxy)]bisphenols included within formula (1) were prepared by the copper catalyzed Ullmann condensation of 4-methoxyphenol with a dihaloaromatic compound followed by demethylation of the resulting bismethyl ether. A less commonly used procedure for the preparation of 4,4'[arylbis(oxy)]bisphenols is the Ullmann condensation of 1-bromo-4-methoxybenzene with a dihydroxyaromatic compound followed by demethylation of the resulting bismethyl ether. The advantage of the second method is that readily available dihydroxyaromatic compounds can be used as starting materials.